This invention relates to a device for continuous injection of fuel into the intake pipe of an internal combustion engine.
Fuel injection devices of similar construction are known in principle from DE-OS No. 29 20 636 and DE-OS No. 32 22 000. In these devices, the fuel is not injected into the intake pipe leading to the cylinders of the internal combustion engine, but is first injected into an air stream which is deviated from the intake piping. The air stream is propelled by an air pump. The mixture thus obtained is then passed into individual injection lines. These injection lines correspond to the individual cylinders of the internal combustion engine, and are in turn connected to the intake pipes just before the intake valves of the cylinders. The advantage of this fuel injection device over conventional fuel injection devices is that no injection nozzles are required for the injection of the fuel-air mix under pressure into the suction pipes corresponding to the individual cylinders. This results from the fact that even small amounts of the mix under pressure expand when entering the suction pipe so that the mix is atomized and sprayed. In addition, the liquid fuel contained in the fuel-air mix is at least partially evaporated during this expansion, which further improves the characteristics of the fuel.
With such fuel injection devices, however, the response characteristics of the internal combustion engine may be adversely affected under certain conditions of operation, especially when the vehicle is coasting. The vehicle is driven in this situation, by the kinetic energy of its own mass, and not by the engine, the throttle valve being shut off. The fuel metering device is shut off to reduce fuel consumption while the air pump continues running, so that all the fuel in the piping between the mixing device and the point of injection is carried into the cylinders of the internal combustion engine. After the coasting operation ends and fuel metering is resumed by the metering device, the fuel requires a certain time to reach the admission line and the cylinders from the point of supply through the mix piping system, resulting in a delay in the response characteristics of the internal combustion engine.